In a turbine or a compressor, a flow of working medium is admitted to a flow duct formed between a casing and an impeller or rotor. In this case, the flow duct extends along an axis of the compressor or turbine. Blades which are subjected to the flow of the working medium extend along a radius in the flow duct. These blades may be guide blades fastened to the casing or moving blades fastened to the impeller or rotor. The guide blades serve to influence the flow of the working medium. The moving blades are subjected to the flow of the working medium.
In the case of a compressor, the moving blades are set in rotary motion by the impeller and in this way compress the flow of the working medium.
In the case of a turbine, the flowing working medium delivers its kinetic energy to the moving blades, which in this way set the rotor in a rotary motion. The rotary motion of the rotor may be used, for example, for driving a generator and for generating electricity in the process.
A number of blades normally form a blade ring in which the number of blades are placed next to one another in a ring shape along the circumference of the flow duct and are fastened to the casing in the case of guide blades or to the rotor or impeller in the case of moving blades. An expedient number of such blade rings depending on the application are arranged one behind the other in a stepped manner along the axis of a compressor or a turbine. Here, the design and orientation of a blade of a blade ring expediently varies from step to step in accordance with the pressure and temperature ratios of the flow of the working medium along the flow duct. Between a first and a second blade ring arranged along the axis there is an intermediate space in which the medium flows freely.
In the intermediate space, a blade is fastened with its root to the impeller or casing. The fastening can be locked by a plate being bent over in the intermediate space, for example into a gap made at the casing or impeller. This is the case in particular in a compressor. For fitting or removal during production or inspection, such a locking plate has hitherto been bent over manually. To this end, a bending tool in the form of a bar or a suitable lever is positioned at the plate to be bent in an intermediate space between two blade rings arranged along an axis of the compressor and having blades extending along a radius. The plate is then bent over manually by striking the bending tool with a hammer.
This bending operation has to be carried out individually for each locking plate. Of course, on account of the manual activity, defined and reproducible bending-over at a series of plates cannot be ensured. There is also the fact that the manual activity leads to a comparatively long fitting time. The lever forces to be applied are partly so high that, if the lever slips off, there is a comparatively high risk of injury to the fitter and/or a blade of the compressor may be damaged. The impeller or the wheel disk provided for accommodating the blades may also be damaged. In addition, cracks may be initiated in the plate due to undefined, manual bending-over, which cracks may possibly impair the service life and reliable functioning of said plate.
The situation is similar with a bending operation on a plate in an intermediate space in a turbine.
It would be desirable to avoid these disadvantages and improve the bending operation.